Parallel guide for surgical implants

ABSTRACT

Disclosed herein is a parallel spacer for parallel spacing of a guide wire/pin during surgery. The parallel spacer incudes a parallel spacer body having a top surface and a bottom surface. The parallel spacer also includes a first aperture extending through the body and defined by one or more internal walls that extends to the opening in the top surface. The aperture is sized to receive a first guide and hold the first guide in a first orientation. A second aperture extends between a second opening in the top surface and a second opening in the bottom surface. The second aperture is defined by one or more walls located within the spacer body. The one or more walls connect the second opening in the top surface to the second opening in the bottom surface. The aperture is sized to receive another guide and hold the other guide in a parallel orientation to the first orientation at a first distance from the first aperture. A third aperture extends between a third opening in the top surface and a third opening in the bottom surface. The third aperture is defined by one or more walls located within the spacer body. The one or more walls connect the third opening in the top surface to the third opening in the bottom surface. The aperture is sized to receive another guide and hold the other guide in a parallel orientation to the first orientation at a second distance from the first aperture. The parallel spacer also includes at least two spacer markings. A first spacer marking is positioned adjacent to the second aperture and a second spacer marking is positioned adjacent to the third aperture. Each of the two spacer markings mark the first distance and the second distance.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/799,419, filed Oct. 31, 2017, entitled Parallel Guide forSurgical Implants, now U.S. Pat. No. 10,603,054, which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to orthopedic surgery. Morespecifically, techniques, devices, and systems associated with theparallel implantation of a bone screw for joint fusion are described.

BACKGROUND

Stress across joints and in particular the sacroiliac joint generally isa common cause of pain including lower back pain. Various types ofsacroiliac joint stress, including sacroiliac joint disruptions (i.e.,separations) and degenerative sacroiliitis (i.e., inflammation) canresult from lumbar fusion, trauma, postpartum, heavy lifting, arthritis,or unknown causes. Sacroiliac joint fixation or arthrodesis is sometimesrecommended for skeletally mature patients with severe, chronicsacroiliac joint pain or acute trauma in the sacroiliac joint.

Conventional solutions for stabilizing joints and relieving pain injoints typically include the insertion of an implant, such as a metalscrew, rod or bar, laterally across the joint. As multiple implants maybe inserted across the joint, the relative orientation between theimplants needs to be controlled. Guides that utilize a sliding mechanismare known. But such guides do not provide both flexibility and thecontrol of discrete placement of the guides used for locating implants.

SUMMARY

The summary is illustrative only and is not intended to be in any waylimiting. In addition to the illustrative aspects, embodiments, andfeatures described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

In accordance with various embodiments, the parallel spacer incudes aparallel spacer body having a top surface and a bottom surface. Theparallel spacer also includes a first aperture extending through thebody and defined by one or more internal walls that extends to theopening in the top surface. The aperture is sized to receive a firstguide and hold the first guide in a first orientation. A second apertureextends between a second opening in the top surface and a second openingin the bottom surface. The second aperture is defined by one or morewalls located within the spacer body. The one or more walls connect thesecond opening in the top surface to the second opening in the bottomsurface. The aperture is sized to receive another guide and hold theother guide in a parallel orientation to the first orientation at afirst distance from the first aperture. A third aperture extends betweena third opening in the top surface and a third opening in the bottomsurface. The third aperture is defined by one or more walls locatedwithin the spacer body. The one or more walls connect the third openingin the top surface to the third opening in the bottom surface. Theaperture is sized to receive another guide and hold the other guide in aparallel orientation to the first orientation at a second distance fromthe first aperture. The parallel spacer also includes at least twospacer markings. A first spacer marking is positioned adjacent to thesecond aperture and a second spacer marking is positioned adjacent tothe third aperture. Each of the two spacer-markings mark the firstdistance and the second distance.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several examples in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings, in which:

FIG. 1A is a perspective view of a parallel guide for joint fusionaccording to one embodiment;

FIG. 1B is a proximal view thereof;

FIG. 1C is a side view thereof;

FIG. 1D is a front view thereof;

FIG. 1E is a cross-section side view taken along cross section line A-Aof FIG. 1C;

FIG. 2A is a perspective view of a parallel guide for joint fusionaccording to one embodiment;

FIG. 2B is a proximal end view thereof;

FIG. 2C is a side view thereof;

FIG. 2D is a side view thereof;

FIG. 2E is a cross-section view taken along line B-B of FIG. 2B;

FIG. 2F is a cross-section view taken along line C-C of FIG. 2B

FIG. 3 illustrates a guide pin being set in a sacroiliac joint accordingto one embodiment of a surgical procedure for joint fusion;

FIG. 4A illustrates a depth gauge according to one embodiment fordetermining the depth of a pilot hole to be drilled for insertion of acage for joint fusion;

FIG. 4B is a view thereof installed over a guide being set in asacroiliac joint in the procedure of FIG. 3;

FIG. 5A illustrates a tissue protector according to one embodiment, and

FIG. 5B is a view thereof placed over a guide and set in a sacroiliacjoint in the procedure of FIG. 3;

FIG. 6A is a perspective view of a cannulated drill bit for drilling apilot hole for insertion of a cage for joint fusion according to oneembodiment and

FIG. 6B is a side view thereof being placed over the guide for drillinga pilot hole for insertion of a cage for joint fusion in the procedureof FIG. 3;

FIG. 7A is a perspective view of a driver for driving a bone cage forinsertion of the cage for joint fusion according to one embodiment;

FIG. 7B is a perspective view of a bone cage shown in FIG. 7A;

FIG. 7C is a side view of the driver of FIG. 7A driving a bone cage intoa joint for fusion in the procedure of FIG. 3;

FIG. 8A is a perspective view of a parallel guide according to oneembodiment being used to set a guide at a new location in a sacroiliacjoint in the procedure of FIG. 3;

FIG. 8B is a perspective view of a parallel guide according to anotherembodiment being used to set a guide at a new location in a sacroiliacjoint in the procedure of FIG. 3; and

FIG. 9 illustrates a packing plunger assembly according to oneembodiment placed in a tissue protector assembly for packing a cage forjoint fusion in the procedure of FIG. 3.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative examples described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherexamples may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areimplicitly contemplated herein.

Techniques for joint fusion are described, including systems,apparatuses and processes for fusing a joint. Systems and apparatusesfor fusing a joint include a cage (i.e., a cannulated cage), a tissueprotector assembly, a guide, a depth gauge, a cannulated drill bit(e.g., an adjustable cannulated drill bit that employs a stop collar), adriver, a parallel guide, and a plunger distance tool. As used herein,the term “cannulated” refers to having a cannula, or a hollow shaft. Insome examples, the cage may be inserted or implanted into tissue (e.g.,bone, cartilage, or other tissue in the joint). As used herein, the term“implant” or “implantation” refers to inserting or insertion into a partof a body. For example, a bone cage may be implanted into a joint (e.g.,a sacroiliac joint). In some examples, the cage may have a cannula andradial fenestrations in which therapeutic materials may be packed. Suchtherapeutic materials may include osteogenic compounds (e.g., bonemorphogenetic protein, or other osteogenic compounds that may ossifytissue in the joint), osteoconductive materials (e.g., demineralizedbone, hydroxyapatite, or other material that promotes bone growth),antibiotics, steroids, contrast materials, or other materials that maybeneficial to fusing the joint, treating inflammation or otherconditions in the joint, or enabling the visualization of the areawithin and adjacent to an implanted bone cage. In some examples, thebone cage may be a screw or screw type device having threads. In someexamples, the screw may have one or more rows or groups of helicalfenestrations along the wall (i.e., the shaft of the cage defining thecannula) of its shaft to allow the material packed inside the cannula ofthe cage to contact (e.g., touch, seep into, affect, communicate with,or otherwise physically contact) tissue adjacent to, surrounding, oreven within, the cage. In some examples, various tools may be used toinsert a cage into a location on a joint, and to prepare the locationfor the insertion procedure. Such tools may include an implantationassembly, which may comprise a tissue protector; a guide; a depth gauge;a cannulated drill bit; a driver; a parallel guide; a packing plunger,which may comprise a packing tube, a plunger and a loading port; aplunger distance tool; and other tools.

In some examples, a guide may be inserted first into a joint at adesired location, in a lateral position across the joint. In someexamples, a tissue protector assembly may be used, along with the guide,to guide the preparation (i.e., drilling) of a pilot hole as well as toguide insertion of a cannulated cage or other implant while forming abarrier between the preparation site and the surrounding tissue. In someexamples, a cannulated drill bit may be used with the tissue protectorand/or guide to drill the pilot hole. In some examples, a driver orscrew driver may be used to insert the cage into the pilot hole. Theterms “driver” is used herein to refer to a tool with a tip configuredto engage the head of a screw or similar device, the tool being usefulfor rotating a screw or otherwise manipulating the screw to drive thescrew or, in this case, cage into place in a joint. In some examples, aparallel spacer device may be used to space another guide in preparationfor insertion of another cage. In some examples, a packing plungerassembly may be used to pack the cage with the above-mentionedmaterials. The packing plunger may be used to pack materials into thecage either or both pre- and post-insertion of the cage into the joint,and may be used with or without the tissue protector assembly.

FIGS. 1A-E are various views of a parallel guide 300 for joint fusionaccording to one embodiment. Here, the parallel guide 300 includes aparallel spacer body 310 and an external positioning protrusion 320. Inaccordance with various embodiments, the parallel spacer body 310includes a plurality of apertures (e.g., apertures 330 or 332-338)suitable to receive one or more guides (e.g., guide pins 418 a or 418 bshown in FIGS. 3 and 8A). In accordance with various embodiments, theexternal positioning protrusion 320 extends from the parallel spacerbody 310 and is suitable to engage with a tissue protector 400. In someexamples, parallel guide 300 may be configured to place another or anext guide at a distance from a previously placed implant (i.e., apreviously implanted screw or cage). Like-numbered and named elements inthis view may describe the same or substantially similar elements as inprevious or subsequent views.

In accordance with various embodiments, the parallel spacer body 310includes a proximal surface 312 and a distal surface 314. While shown asopposing flat parallel surfaces, it is appreciated that these surfacescan have other suitable profiles, such as concave, convex and irregularsurfaces. In accordance with various embodiments, the parallel spacerbody 310 has a sufficient thickness to hold a guide in a substantiallyconstant angular position relative to the parallel guide 300. Theparallel spacer body 310 can be any suitable shape to position each ofthe various apertures therethrough. In one example, the proximal surface312 is a semi-circle defining the overall shape of the parallel spacerbody down to the distal surface 314 which is also a semi-circle. Othershapes, such as circles, polygons (triangles, rectangles, etc.) or lessgeometrical shapes may be suitable as well.

In accordance with various embodiments, the primary guide aperture(e.g., aperture 330) extends through the parallel spacer body 310. Theprimary guide aperture (e.g., aperture 330) includes an axis 330 a thatdefines the orientation of the guide (e.g., guide 418) relative to theparallel guide 300 as the guide passes through the aperture. In someembodiments, the body orientation, i.e. the orientation between theparallel guide 300 (as defined by the upper surface 213) and the guide418 is perpendicular. In other embodiments, there can be an angle lessthan 90 degrees between the two. The primary guide aperture (e.g.,aperture 330) includes an opening 330 b on the proximal end of theparallel guide 300. In one example, the opening 330 b extends into theparallel spacer body 310 from the proximal surface 312. In otherexamples, the opening 330 b may extend into the parallel spacer body 310from any suitable surface on the proximal end of the parallel guide 300,such as a protrusion on the proximal end or like feature. The primaryguide aperture (e.g., aperture 330) includes an opening 330 c on thedistal end of the parallel guide 300. In one example, the opening 330 cextends into the parallel spacer body 310 from any suitable surface onthe distal end of the parallel guide 300. For example, the aperture 330can extend from the opening 330 b to the opening 330 c on distal surface326 on the external positioning protrusion 320. In another example, theopening 330 c may extend from any similar suitable feature, such as fromthe distal surface 314. The primary guide aperture (e.g., aperture 330)is defined by an interior surface 330 d that extends between opening 330b and 330 c.

In accordance with various embodiments, the parallel guide 300 includesone or more subsequent guide apertures (e.g., apertures 332-338). Eachof the plurality of subsequent guide apertures (e.g., apertures 332-338)are fixedly located relative to the primary guide aperture (e.g.,aperture 330) thereby defining a set distance between each of thesubsequent guide apertures (e.g., apertures 332-338) and the primaryguide aperture (e.g., aperture 330). The subsequent guide apertures(e.g., apertures 332-338) may be integrally formed with parallel spacerbody 310 along with the primary guide aperture (e.g., aperture 330) suchthat each distance (e.g., distance 342-348) is constant. In accordancewith various embodiments, each of the subsequent guide apertures (e.g.,apertures 332-338) extends through the parallel spacer body 310. Each ofthe subsequent guide apertures (e.g., apertures 332-338) includes anaxis (e.g., 332 a-338 a respectively) that defines the orientation of anew guide (e.g., guide 418 b) relative to the parallel guide 300 as theguide passes through the aperture. Each of the subsequent guideapertures (e.g., apertures 332-338) includes an opening (e.g., openings332 b-338 b respectively) on the proximal end of the parallel guide 300.In one example, the opening (e.g., any one of openings 332 b-338 b)extends into the parallel spacer body 310 from the proximal surface 312.In other examples, the opening (e.g., any one of openings 332 b-338 b)may extend into the parallel spacer body 310 from any suitable surfaceon the proximal end of the parallel guide 300, such as a protrusion onthe proximal end or like feature. Each of the subsequent guide apertures(e.g., apertures 332-338) includes an opening (e.g., openings 332 c-338c respectively) on the distal end of the parallel guide 300. In oneexample, the opening (e.g., any one of openings 332 c-338 c) extendsinto the parallel spacer body 310 from any suitable surface on thedistal end of the parallel guide 300. In one example, the opening (e.g.,any one of openings 332 c-338 c) extends from the distal surface 314into the parallel spacer body 310. In another example, the aperture(e.g., apertures 332-338) can extend from the opening (e.g., openings332 c-338 c respectively) on a distal surface on a protrusion or likefeature. Each of the subsequent guide apertures (e.g., apertures332-338) are defined by an interior surface (e.g., surface 332 d-338 drespectively) that extends between each respective proximal opening(e.g., openings 332 c-338 c respectively) and each respective distalopening (e.g., openings 332 c-338 c respectively). FIG. 1E illustratesan example showing aperture 335 extending from proximal opening 335 b todistal opening 335 c, defining the interior surface 335 d.

In some examples, parallel spacer body 300 may comprise spacer markings(e.g., markings 332 e-338 e) with numerical labels for measuring out thespacing between the primary guide 418 and the subsequently placed guide418 b. Any subsequently placed guide 418 b is placed in the aperturecorresponding to the spacer marking. The number corresponding to thatmarking may indicate the space (i.e., distance, for example, inmillimeters) between a previously placed guide 418, and the guide 418 bto be placed in subsequent guide aperture (e.g., aperture 332-338).This, in turn, may determine the spacing between an implant (e.g., cageor bone screw) and a next implant (e.g., cage or bone screw). Byutilizing discrete apertures, as opposed to a continuously adjustablemechanism for locating the subsequent guide relative to the primaryguide, consistent control over the surgical procedure can be obtained.

In accordance with one embodiment, the pattern of discrete locations forthe aperture (e.g., aperture 332-338) can form an arc. The primaryaperture (e.g., aperture 330) can be concentric within the arc. In oneembodiment, the concentric location is selected such that there is adifferent distance between the primary aperture (e.g., aperture 330) andeach of the other apertures (e.g., aperture 332-338) extending throughthe guide body 310. This results in a variety of different discretedistances that are usable in the surgical procedure for placing oneguide (e.g., pin 418 b) in a parallel configuration relative to anotherguide (e.g., pin 418). In one example, the distances between the primaryaperture (e.g., aperture 330) and each of the other apertures (e.g.,aperture 332-338) increases as the arc progresses from one side to theother. The markings (e.g., markings 332 e-338 g) indicate thisincreasing distance, as shown by way of example in FIGS. 1A and 1B.

In accordance with various embodiments, the external positioningprotrusion 320 is suitably connected to the parallel spacer body 310 soas to constrain and/or position the tissue protector 400 relative to theparallel spacer body 310. For example, the external positioningprotrusion 320 may be integrally formed with parallel spacer body 310.In one embodiment, the external protrusion may have an outer diametersuitable to be received into the tissue protector 400. In anotherembodiment, the external protrusion may have an inner diameter (e.g.along the aperture 330 which could be stepped in diameters toaccommodate both the guide and the tissue protector) suitable to receivethe tissue protector 400. In various embodiments, the externalpositioning protrusion 320 may function as the primary alignment memberby engaging another alignment entity such as a drill guide or tissueprotector. This allows the second guide 418 b to be set parallelrelative to the other alignment entity.

In some examples, external positioning protrusion 320 may be sized(i.e., have an outer diameter configured) to fit within the cannula of adrill guide, and also may have its own hollow shaft (i.e., an externalpositioning protrusion cannula) configured to fit around or over aguide. FIG. 8A illustrates a view of an exemplary parallel guide 300 forplacement of another guide as placed on a drill guide: the parallelspacer body 310, external positioning protrusion 320, primary guideaperture 330, subsequent guide aperture 332, tissue protector 404,handle 412, and guide 418 b. As shown, external positioning protrusion320 may fit into tissue protector 404. In some embodiments, part ofparallel spacer body may rest against tissue protector. In variousembodiments, guide 418 may be inserted into the joint (e.g., bythreading, hammer, pressing or similar method). A depth gauge may beused to measure the depth of the guide 418 into the joint. In someembodiments, the tissue protector 404 may be slid over the depth gauge602 to locate the tissue protector 404, or in other embodiments, thetissue protector 404 may be located first and then the guide (e.g. pin418) and depth gauge 602 are inserted into the tissue protector 404. Theexternal positioning protrusion 320 may fit over guide 418 via aperture330. In some examples, parallel guide 300 is placed on tissue protector404. In some embodiments, external positioning protrusion 320 may beinserted into the tissue protector. The external positioning protrusion320 may flex by closing the slot 324 as it is forced into the tissueprotector with the annular ridge 322 engaging the internal wall of thetissue protector 404. A next guide 418 b, as shown in FIG. 8A, may beinserted through any one of the subsequent guide apertures (e.g., anyone of apertures 332-338) until the end of the next guide 418 b restsagainst a bone (i.e., an ilium). While in place in subsequent guideaperture (e.g., any one of apertures 332-338), the next guide 418 b maybe advanced into the bone and through a joint to a desired depth (e.g.,using a mallet or other suitable method).

In some examples, parallel spacer body 300 may comprise spacer markings(e.g., markings 332 e-338 g) with numerical labels for measuring out thespacing between the primary guide 418 and the subsequently placed guide418 b. Any subsequently placed guide 418 b is placed in the aperturecorresponding to the spacer marking. The number corresponding to thatmarking may indicate the space (i.e., distance, for example, inmillimeters) between a previously placed guide 418, and the guide 418 bto be placed in subsequent guide aperture (e.g., aperture 332-338).This, in turn, may determine the spacing between an implant (e.g., cageor bone screw) and a next implant (e.g., cage or bone screw).

FIGS. 2A-F are various views of a parallel guide for joint fusionaccording to one embodiment. Here, the parallel guide 350 includes aparallel spacer body 360 and an external positioning protrusion 370. Inaccordance with various embodiments, the parallel spacer body 310includes a plurality of apertures (e.g., apertures 380 or 382-337)suitable to receive one or more guides (e.g., guides 418 a or 418 bshown in FIGS. 3 and 8B). In accordance with various embodiments, theexternal positioning protrusion 370 extends from the parallel spacerbody 360 and is suitable to engage with a tissue protector 400. In someexamples, parallel guide 350 may be configured to place another or anext guide at a distance from a previously placed implant (i.e., apreviously implanted screw or cage). Like-numbered and named elements inthis view may describe the same or substantially similar elements as inprevious or subsequent views.

In accordance with various embodiments, the parallel spacer body 360includes a proximal surface 362 and a distal surface 364. While shown asopposing flat parallel surfaces, it is appreciated that these surfacescan have other suitable profiles, such as concave, convex and irregularsurfaces. In accordance with various embodiments, the parallel spacerbody 360 has a sufficient thickness to hold a guide in a substantiallyconstant angular position relative to the parallel guide 350. Theparallel spacer body 360 can be any suitable shape to position each ofthe various apertures therethrough. In one example, the proximal surface362 is an elongated rectangle defining the overall shape of the parallelspacer body down to the distal surface 364 which is also a semi-circle.Other shapes, such as circles, polygons (triangles, other rectangles,etc.), or less geometrical shapes may be suitable as well.

In accordance with various embodiments, the primary guide aperture(e.g., aperture 380) extends through the parallel spacer body 360. Theprimary guide aperture (e.g., aperture 380) includes an axis 380 a thatdefines the orientation of the guide (e.g., guide 418) relative to theparallel guide 350 as the guide passes through the aperture. The primaryguide aperture (e.g., aperture 380) includes an opening 380 b on theproximal end of the parallel guide 350. In one example, the opening 380b extends into the parallel spacer body 360 from the proximal surface362. In other examples, the opening 380 b may extend into the parallelspacer body 360 from any suitable surface on the proximal end of theparallel guide 350, such as a protrusion on the proximal end or likefeature. The primary guide aperture (e.g., aperture 380) includes anopening 380 c on the distal end of the parallel guide 350. In oneexample, the opening 380 c extends into the parallel spacer body 360from any suitable surface on the distal end of the parallel guide 350.For example, the aperture 380 can extend from the opening 380 b to theopening 380 c on distal surface 376 on the external positioningprotrusion 370. In another example, the opening 380 c may extend fromany similar suitable feature, such as from the distal surface 364. Theprimary guide aperture (e.g., aperture 380) is defined by an interiorsurface 380 d that extends between opening 380 b and 380 c.

In accordance with various embodiments, the parallel guide 350 includesone or more subsequent guide apertures (e.g., apertures 382-387). Eachof the plurality of subsequent guide apertures (e.g., apertures 382-387)are fixedly located relative to the primary guide aperture (e.g.,aperture 380) thereby defining a set distance between each of thesubsequent guide apertures (e.g., apertures 382-387) and the primaryguide aperture (e.g., aperture 380). The subsequent guide apertures(e.g., apertures 382-387) may be integrally formed with parallel spacerbody 360 along with the primary guide aperture (e.g., aperture 380) suchthat each distance (e.g., distance 392-398) is constant. In accordancewith various embodiments, each of the subsequent guide apertures (e.g.,apertures 382-387) extends through the parallel spacer body 310. Each ofthe subsequent guide apertures (e.g., apertures 382-387) includes anaxis (e.g., 382 a-387 a respectively) that defines the orientation of anew guide (e.g., guide 418 b) relative to the parallel guide 350 as theguide is located through the aperture. Each of the subsequent guideapertures (e.g., apertures 382-387) includes an opening (e.g., openings382 b-387 b respectively) on the proximal end of the parallel guide 300.In one example, the opening (e.g., any one of openings 382 b-387 b)extends into the parallel spacer body 360 from the proximal surface 362.In other examples, the opening (e.g., any one of openings 382 b-387 b)may extend into the parallel spacer body 360 from any suitable surfaceon the proximal end of the parallel guide 350, such as a protrusion onthe proximal end or like feature. Each of the subsequent guide apertures(e.g., apertures 382-387) includes an opening (e.g., openings 382 c-387c respectively) on the distal end of the parallel guide 350. In oneexample, the opening (e.g., any one of openings 382 c-387 c) extendsinto the parallel spacer body 360 from any suitable surface on thedistal end of the parallel guide 350. In one example, the opening (e.g.,any one of openings 382 c-387 c) extends from the distal surface 364into the parallel spacer body 360. In another example, the aperture(e.g., apertures 382-387) can extend from the opening (e.g., openings382 c-387 c respectively) on a distal surface on a protrusion or likefeature. Each of the subsequent guide apertures (e.g., apertures382-387) is defined by an interior surface (e.g., surface 338 d-387 drespectively) that extends between each respective proximal opening(e.g., openings 382 c-387 c respectively) and each respective distalopening (e.g., openings 382 c-387 c respectively).

FIG. 2E is a cross-section view taken along line B-B of FIG. 2B. FIG. 2Eillustrates an example showing apertures 385, 386, and 387 extendingfrom proximal openings 385 b, 386 b and 387 b respectively to distalopenings 385 c, 386 c and 387 c respectively, defining the interiorsurface 385 d, 386 d, and 387 d respectively. FIG. 2F is a cross-sectionview taken along line C-C of FIG. 2B. FIG. 2F illustrates an exampleshowing apertures 384, 383, and 382 extending from proximal openings 384b, 383 b and 382 b respectively to distal openings 384 c, 383 c and 382c respectively, defining the interior surface 384 d, 3863, and 382 drespectively.

In some examples, parallel spacer body 350 may comprise spacer markings(e.g., markings 382 e-387 g) with numerical labels for measuring out thespacing between the primary guide 418 and the subsequently placed guide418 b. Any subsequently placed guide 418 b is placed in the aperturecorresponding to the spacer marking. The number corresponding to thatmarking may indicate the space (i.e., distance, for example, inmillimeters) between a previously placed guide 418, and the guide 418 bto be placed in subsequent guide aperture (e.g., aperture 382-387).This, in turn, may determine the spacing between an implant (e.g., cageor bone screw) and a next implant (e.g., cage or bone screw). Byutilizing discrete apertures, as opposed to a continuously adjustablemechanism for locating the subsequent guide relative to the primaryguide, consistent control over the surgical procedure can be obtained.

In accordance with one embodiment, the pattern of discrete locations forthe aperture (e.g., aperture 382-387) can extend from aperture 380 inseparate linear formation. As indicated above, each of the apertures(e.g., apertures 382-387) can form a separate line with aperture 380being the first point and apertures 382-387 being separate distinctseparate points forming separate lines with aperture 380. However, asillustrated in FIGS. 2A-2F, to form a smaller body, 360 each of theapertures (e.g., aperture 382-387) can group together into separatelines. For example half of the apertures can be in one line and half ofthe apertures can be in the other. The apertures can alternate betweenlines with increasing distance from aperture 380. For example, apertures(e.g., apertures 382-387) can increase in distances from aperture 380 inaccording to a progression: aperture 385, then aperture 384, thenaperture 386, then aperture 383, then aperture 387, then aperture 382.But each of apertures 385, 386, and 387 can fall along one line 397 fromaperture 380 and each of apertures 384, 383, and 382 can fall alonganother line 398 from aperture 380. This arrangement allows smallersteps in distances between apertures, without the aperture contactingeach other. In one example, each of the apertures in a line (e.g. line398) are separated from each by about the distance of one aperturediameter. This results in that ability to step the aperturesalternatively between the lines in steps equal to the aperture diameter.In another example, each of the apertures in a line can be separatedfrom one another by a distance of less than the aperture diameter. Thisresults in that ability to step the apertures alternatively between thelines in steps less than the aperture diameter. In another example, eachof the apertures in a line can be separated from one another by adistance of more than the aperture diameter. Additionally, more lines ofapertures can be incorporated. In effect, a combination of guide 300 and350 can be combined with multiple lines forming multiple arcs givingsignificant precision to pin location while still providing discreteapertures for better consistency. The primary aperture (e.g., aperture380) can be concentric within the arc. The markings (e.g., markings 382e-387 g) indicate this increasing distance, as shown by way of examplein FIGS. 2A and 2B.

In accordance with various embodiments, the external positioningprotrusion 370 is suitably connected to the parallel spacer body 360 soas to constrain and/or position the tissue protector 400 relative to theparallel spacer body 360. For example, the external positioningprotrusion 370 may be integrally formed with parallel spacer body 360.

In some examples, external positioning protrusion 370 may be sized(i.e., have an outer diameter configured) to fit within the cannula of adrill guide and also may have its own hollow shaft (i.e., an externalpositioning protrusion cannula) configured to fit around or over aguide. FIG. 8A illustrates a view of an exemplary parallel guide 350 forplacement of another guide as placed on a drill guide: the parallelspacer body 360, external positioning protrusion 370, primary guideaperture 380, subsequent guide aperture (e.g., aperture 382-387), tissueprotector 404, handle 412 and guide 418 b. As shown, externalpositioning protrusion 370 may fit into tissue protector 404. In someembodiments, part of parallel spacer body may rest against tissueprotector. In various embodiments, guide 418 may be inserted into thejoint (e.g., by threading, hammer, pressing or similar method). A depthgauge may be used to measure the depth of the guide 418 into the joint.In some embodiments, the tissue protector 404 may be slid over the depthgauge 602 to locate the tissue protector 404, or in other embodiments,the tissue protector 404 may be located first and then the guide (e.g.pin 418) and depth gauge 602 are inserted into the tissue protector 404.The external positioning protrusion 370 may fit over guide 418 viaaperture 380. In some examples, parallel guide 350 is placed on tissueprotector 404. In some embodiments, external positioning protrusion 370may be inserted into the tissue protector. The external positioningprotrusion 370 may flex by closing the slot as it is forced into thetissue protector with the annular ridge engaging the internal wall ofthe tissue protector 404. A next guide 418 b, as shown in FIG. 8A, maybe inserted through any one of the subsequent guide apertures (e.g., anyone of apertures 382-387) until the end of the next guide 418 b restsagainst a bone (i.e., an ilium). While in place in subsequent guideaperture (e.g., any one of apertures 382-387), the next guide 418 b maybe advanced into the bone and through a joint to a desired depth (e.g.,using a mallet or other suitable method).

In some examples, parallel spacer body 350 may comprise spacer markings(e.g., markings 382 e-387 g) with numerical labels for measuring out thespacing between the primary guide 418 and the subsequently placed guide418 b. Any subsequently placed guide 418 b is placed in the aperturecorresponding to the spacer marking. The number corresponding to thatmarking may indicate the space (i.e., distance, for example, inmillimeters) between a previously placed guide 418, and the guide 418 bto be placed in subsequent guide aperture (e.g., aperture 382-387) This,in turn, may determine the spacing between an implant (e.g., cage orbone screw) and a next implant (e.g., cage or bone screw).

FIG. 3 illustrates an exemplary guide 418. In some examples, guide 418may be a medical grade sterile metal guide such as a wire or pin (e.g.,Kirschner wire, Steinmann pin, or other metal pin) suitable for use inmedical procedures. In some examples, the guide may be another type ofmedical device suitable to forma primary orientation during surgery.Such alternative guides can include drill guides or tissue protectors.In some examples, guide 418 may be used for alignment and guidance of atissue protector (e.g., tissue protector 404), an implant (e.g., a cageor other implant), and other tools into the ilium I, the sacrum S, orthe joint there between. The guide 418 can be set into the patient viatwisting, hammering, pressure or any other suitable method. In aparticular example, mallet 417 drives the guide 418 into the iliumand/or the sacrum. In some examples, guide tip 410 may form a trocar forintroducing tissue protector assembly 400 into a bone.

FIG. 4A illustrates an embodiment of a depth gauge 602 for determiningthe depth of a guide to be inserted into the ilium I and/or sacrum S. Invarious embodiments, depth gauge 602 includes depth markings 604,channel 606, and distal contact surface 607. In various examples, thechannel 606 is formed along an exposed wall 609 of the depth gage. Thechannel 606 transitions into an enclosed channel through a lower bodyportion 611. The contact surface 607 is located on the distal end of thelower body portion 611 and is suitable to contact the ilium I. The guide418 may then be slid into the depth gauge 602 to the desired depth asmeasured on the depth markings 604. In some examples, depth gauge 602may be configured to determine the depth in which guide 418 is insertedinto a bone and/or joint. In some examples, depth gauge 602 may includedepth markings 604, which can measure the depth in which the guide 418is driven into the ilium. In some examples, depth markings 604 mayindicate a range of 25-65 mm depths. In other examples, depth gauge 602may have different depth markings, and thus indicate a different rangeof depths. The number in depth markings 604 that corresponds to thelocation of the end of guide 418 may indicate the depth of guide 418. Inother examples, depth markings 604 can indicate a different depth thatmay correspond and be calibrated to the depth of guide 418 (e.g., depthmarkings 604 may indicate a desired drilling depth for a pilot hole, adepth of a cage to be implanted, or other depth that is associated withthe depth of guide 418, and may thus be measured against the depth ofguide 418). In still other examples, depth gauge 602 may include more orfewer elements and is not limited to the examples described.

FIGS. 5A and 5B illustrate a tissue protector assembly 400. The tissueprotector assembly may include sleeve 404 and handle 412. In someexamples, tissue protector sleeve 404 may include a tissue protectorhead 414, and tissue protector tip 416. In some examples, sleeve 404 hasa hollow shaft 415 having a close fit to one or more of the depth gauge602, the cage 100, and or a drill 700. In some embodiments, the guide481 may be utilized with a guide sleeve. The guide sleeve can receiveinto the guide sleeve. The guide sleeve can then be inserted into thetissue protector. In various embodiments, the guide sleeve includes aclose tolerance to the interior of the channel 415 of the tissueprotector so that the guide is accurately positioned in the tissueprotector 404. In some embodiments, the guide 418 is centered in thetissue protector 400. In other embodiments, the depth gauge 602functions as the guide sleeve. In some examples, the outer diameter ofsleeve (e.g., depth gauge 602) shaft is shaped to fit inside the cannulaof tissue protector 400, which has an internal diameter that may beconfigured to accommodate tools and implants (e.g., cages 100, and thelike) having a larger diameter than a guide. For example, the diameterof tissue protector 404's cannula 415 may correspond to (i.e., be sizedto fit) the head or outer diameter on an implant (e.g., cages 100). Insome examples, the internal surface of tissue protector 400 may beconfigured to guide an implant (e.g., cage 100) inserted into tissueprotector 400 from tissue protector head 414 and through to tissueprotector tip 416.

In some examples, tissue protector tip 416 may have spikes, teeth,wedges, or other structures, to engage a bone. As shown, tissueprotector tip 416 is engaged with an ilium (i.e., its spikes, teeth,wedges or other structure for engaging a bone, are embedded in theilium). In some embodiments, the tissue protector tip 416 does not embedinto the bone but merely increases friction such that the tissueprotector tip 416 does not slip on the exterior of the bone. In otherexamples, tissue protector assembly 400 may be formed differently and isnot limited to the examples described.

FIG. 5B illustrates an exemplary tissue protector assembly placed over aguide. Here, diagram 420 may include tissue protector sleeve 404, handle412, tissue protector head 414, tissue protector tip 416 and guide 418and depth gage 602 (functioning as a guide sleeve for a pin or wire).Like-numbered and named elements in this view may describe the same orsubstantially similar elements as in previous views (e.g., FIG. 4A).

FIGS. 6A and 6B illustrates a side view of an exemplary cannulated drillbit and for drilling a pilot hole for insertion of a cage for jointfusion. Here, cannulated drill bit 700 may include cutting tip 702, body704, and shank 709. As used herein, “drill bit” refers to any cuttingtool configured to create substantially cylindrical holes, and “shank”refers to an end of the drill bit, usually the end opposite the cuttingtip, configured to be grasped by a chuck of a drill, handle or othertorque applying device. In some examples, cannulated drill bit 700 maybe configured to drill a pilot hole to a predetermined depth. Forexample, cutting tip 702 may be configured to cut cylindrical holes intoa bone and/or joint when torque and axial force is applied to rotatecutting tip 702 (i.e., by a drill). In some examples, cannulated drillbit 700 may be adjustable, and thereby configured to drill a range ofdepths using depth markings. The outside diameter of cannulated drillbit 700 may be configured to fit within a tissue protector (e.g., tissueprotector 400). In some examples, the outside diameter may besignificantly smaller than the tissue protector 400, such that thetissue protector does not provide significant support to the drill bit700 or function as the primary locating tool for the drill bit 700. Inother examples, the tissue protector 400 may function as the drillguide, providing significant support and locating functionality to thedrill bit 700 by having an inner diameter that is substantially the samesize as the outer diameter of the drill bit 700. The variance in sizesbeing sufficient to allow the drill bit 700 to slide and rotate withinthe tissue protector.

In some examples, a desired drilling depth (i.e., depth of a pilot hole)may be the same or similar to the depth of a guide that has beeninserted into a bone and/or joint. In other examples, the desireddrilling depth may be offset (i.e., less deep) by a predetermined amount(e.g., a few millimeters or other offset amount). For example, if aguide has been inserted 40 mm deep into the sacroiliac joint, acorresponding desired drilling depth for the pilot hole may be 40 mm, orit may be 40 mm minus the predetermined offset may be selected (i.e., ifthe predetermined offset is 3 mm, then the desired drilling depth inthis example would be 37 mm).

The cannulated drill bit 700 includes cannula 714. In some examples,cannula 714 are sized to fit over a guide (e.g., guide 418). A driverhandle 906 may receive the shank 709 allowing a user to apply a torqueto the drill bit 700. The drill bit 700 may be slid down over the guidewire 418 thereby accurately locating the drill bit 700 based on theinsertion location of the guide wire 418 into the bone. Tissue protector400, particularly the sleeve 404 thereof protects the tissue surroundingthe drill site from being damaged by the drilling action. The drill maythan form hole through one or more bones (e.g., ilium I and/or SacrumS).

FIGS. 7A and 7C illustrate an exemplary driver 902 for inserting animplant into the joint for fusion. As used herein a cage 100 is providedas an example but it is noted that bone screws for joint fusion can alsobe used in accordance with the various embodiments discussed herein. Thebone cage 100 is further disclosed in co-pending application entitled“Bone Cage With Helically Arranged Fenestrations” having applicationSer. No. 15/798,984 filed herewith on the same date, which isincorporated herein by reference in its entirety. For referencepurposes, FIG. 7B illustrate a perspective view of an exemplary bonecage 100. In accordance with various embodiments, the cage 100 includeshead 102, tip 104, one or more groups of helical fenestrations (e.g.,fenestration groups 107-110), threads 112, and tapered end 120. In someexamples, cage 100 may be fabricated, manufactured, or otherwise formed,using various types of medical grade material, including stainlesssteel, plastic, composite materials, or alloys (e.g., Ti-6Al-4V ELI,another medical grade titanium alloy, or other medical grade alloy) thatmay be corrosion resistant and biocompatible (i.e., not having a toxicor injurious effect on tissue into which it is implanted). In someexamples, threads 112 may be a helical ridge wrapped around an outersurface of cage 100's shaft. In some examples, cage 100 may becannulated having a cannulated opening 124 formed by a hollow shaft thatextends from head 102 to tip 104. Cage 100 may vary in length (e.g.,ranging from approximately 25 mm to 50 mm, or longer or shorter) toaccommodate size and geometric variance in a joint. Other dimensions ofcage 100, including major 132 and minor 133 diameters of threads 112,also may vary to accommodate size and geometric variance in a joint. Insome examples, an outer surface of cage 100's shaft may taper from head102 to tapered end 120, and thus threads 112 also may taper (i.e., be atapered thread) from head 102 to tapered end 120 (e.g., having a rangeof major and minor diameters from head 102 to tapered end 120). In someexamples, the tapering of threads 112, as well as tapered end 120, aidsin guiding the cage through a pilot hole. In other examples, head 102and threads 112 may be sized to fit within a tool or instrument, forexample, a tissue protector 400, as described herein.

In some examples, cage 100's hollow shaft, or cannula, may be accessed(i.e., for packing material into) through an opening 124 in head 102. Insome examples, head 102 may have a flat or partially flat surface (e.g.,pan-shaped with rounded edge, unevenly flat, or other partly flatsurface). In other examples, head 102 may have a different shape (e.g.,dome, button, round, truss, mushroom, countersunk, oval, raised, bugle,cheese, fillister, flanged, or other cage head shape). In some examples,the opening in head 102 may have a receiving apparatus for a torqueapplying tool, such as driver. The driver may be flat head, Phillip'shead, square head, hexagonal, head or any similar shape suitable toreceive a tool and apply torque therefrom. In one example, the torqueapplying tool may be a driver having a TORX® or TORX®-like shape (i.e.,six-point or six-lobed shape) (see FIG. 1D) configured to receive thetip of a TORX® or TORX®-like screwdriver (e.g., driver 902). Forexample, cage 100 may include head grooves 118 a-118 f which may startat head 102 and extend linearly into the cannula of cage 100 to receivecomplementary lobes on the end of a screwdriver. For a TORX® orTORX®-like opening there may be six (6) total head grooves, including,for example, head grooves 118 a-118 f, to receive the complementarylobes on the tip of a TORX® or TORX®-like driver. In some examples, asshown in FIG. 1C, the opening in head 102 may be contiguous with, andform a top end of, cage 100's cannula. For example, the opening mayprovide access to the cannula, for example, to pack material into thecage. The opening may also include a chamfer 119 providing a lead-in fora tool into the head grooves.

As described herein, the therapeutic materials may include osteogeniccompounds (e.g., bone morphogenetic protein, or other osteogeniccompounds that may ossify tissue), osteoconductive materials (e.g.,demineralized bone, hydroxyapatite, or other material that promotes bonegrowth), antibiotics, steroids, contrast materials, or other materialsthat may be beneficial to fusing the joint, treating inflammation orother conditions in the joint, or enabling the visualization of the areawithin and adjacent to the cage. For example, an osteogenic compound,such as bone morphogenetic protein or other compounds, may be packedinto cage 100's cannula such that when cage 100 is inserted into a jointor traverses through a joint (e.g., a sacroiliac joint), the osteogeniccompound, for example through fenestrations (e.g., fenestrations 107a-107 h, 108 a-108 h, 109 a-109 h, and/or 110 a-110 h), may come intocontact with tissue in the joint adjacent to or surrounding cage 100,and ossify the tissue to fuse the joint across and through the cage. Insome examples, the osteogenic compound may enter the joint and may fillthe joint, partially or entirely. In other examples, an osteoconductivematerial, such as demineralized bone or hydroxyapatite or othermaterials may be packed into cage 100's cannula. When cage 100 isinserted into a joint (e.g., the joint between ilium I and sacrum S),the osteoconductive material may come into contact with tissue in thejoint adjacent to or surrounding cage 100, for example throughfenestrations (e.g., fenestrations 107 a-107 h, 108 a-108 h, 109 a-109h, and/or 110 a-110 h), and promote bone growth into the cage and thejoint to fuse the joint across and through the cage. In still otherexamples, a substance for treating sacroilitis, such as steroids orantibiotics or other substances, may be packed into cage 100's cannulasuch that when cage 100 is inserted into the joint, the substance maycome into contact with tissue in the joint adjacent to or surroundingcage 100, for example through fenestrations (e.g., fenestrations 107a-107 h, 108 a-108 h, 109 a-109 h, and/or 110 a-110 h), and treat theinflamed joint tissue. In yet other examples, a contrast material may bepacked into cage 100's cannula such that, when cage 100 is inserted intothe joint, the contrast material within cage 100, and in some examplesabsorbed by tissue adjacent to or surrounding cage 100, may be viewedusing visualization techniques (e.g., x-ray, fluoroscope, ultrasound, orother visualization technique). In still other examples, differentmaterials may be packed into cage 100 for different purposes. In yetother examples, the above-described materials may also come into contactwith tissue adjacent to, or surrounding, cage 100 through an opening attip 104. As described herein, cage 100 may be packed with material priorto being inserted into the joint, and may also be packed after insertioninto the joint. Also as described herein, such materials may be packedinto cage 100 using a packing plunger 1102 (see, e.g., FIG. 9).

In some examples, fenestrations (e.g., fenestrations 107 a-107 h, 108a-108 h, 109 a-109 h, and/or 110 a-110 h) may provide therapeuticopenings in cage 100's shaft to enable material packed inside cage 100to come into contact with surrounding or adjacent tissue (e.g., bone,cartilage, or other tissue in the joint) when cage 100 is implanted.Additionally or alternatively, in various examples, the fenestrations(e.g., fenestrations 107 a-107 h, 108 a-108 h, 109 a-109 h, and/or 110a-110 h) may be shaped to provide additional cutting edges or edgessuitable to clean threads formed by the tip 120. In various examples,fenestrations (e.g., fenestrations 107 a-107 h, 108 a-108 h, 109 a-109h, and/or 110 a-110 h) are substantially circular. In other examples,the fenestrations (e.g., fenestrations 107 a-107 h, 108 a-108 h, 109a-109 h, and/or 110 a-110 h) are oblong (e.g., substantially oval,substantially elliptical, or other suitable shapes). In other examples,fenestrations (e.g., fenestrations 107 a-107 h, 108 a-108 h, 109 a-109h, and/or 110 a-110 h) are shaped differently (e.g., rectangular,rounded rectangular, squared, triangular, or other suitable shapes). Inaccordance with various embodiments and discussed herein

As illustrated in FIGS. 7A and 7C, driver assembly 900 includes driver902, mating tip 904, driver handle 906, tissue protector 404, handle412, and tissue protector head 414. In some examples, driver 902 may beconfigured to drive a cage (e.g., cages 100) into a bone and/or joint.In some examples, driver 902 may have a shaft configured to fit or slidewithin tissue protector 404. In some examples, mating tip 904 may beshaped to engage (i.e., fit) a head of a cage (e.g., head 102). Forexample, driver 902 may be a TORX® driver and mating tip 904 may beshaped to fit a TORX® head cage (e.g., with a six-point or six-lobedshape). In other examples, mating tip 904 may be shaped differently toengage suitable types of cages (e.g., PHILLIPS™ (i.e., having acruciform or cross shape with four lobes), slot, flat, Robertson, hex,or other type of cages). In some examples, driver handle 906 may be usedto turn driver 902, and consequently turn a cage engaged by mating tip904. In some examples, driver 902 may be a manual driver. In otherexamples, driver 902 may be powered (i.e., electrically). In someexamples, driver 902 also may be ratcheting or torque-limited. In someexamples, driver handle 906 may be formed separately from driver 902'sshaft and driver tip 904. In some examples, handle 906 may be configuredto be removably coupled with various types of drivers (e.g., TORX®,PHILLIPS™, slot, flat, Robertson, hex, or other types of cage drivers).In other examples, driver 902 and driver handle 906 may be formeddifferently, and are not limited to the examples shown and described.The cage 100 includes a cannula that slides over the guide wire 418 andinto tissue protector sleeve 404. The driver 902 forces the cage 100down sleeve 404 until contact is made with the bone. Then a torque isapplied to cage 100 by the handle 906 causing the cage to twist into thebone.

FIG. 8A is a perspective view of a parallel guide 300 according to oneembodiment being used to set another guide at a new location in asacroiliac joint in the procedure of FIG. 3. This embodiment of theparallel guide 300 corresponds to the parallel guide illustrated inFIGS. 1A-E and discussed in more detail above.

FIG. 8B is a perspective view of a parallel guide according to anotherembodiment being used to set a guide at a new location in a sacroiliacjoint in the procedure of FIG. 3. This embodiment of the parallel guide350 corresponds to the parallel guide illustrated in FIGS. 2A-F anddiscussed in more detail above.

FIG. 8A illustrates a side view of the parallel guide 300 for placementof another guide 418 b. FIG. 9 illustrates a second guide 418 b placedparallel to the first setup. This is accomplished by running theadditional guide 418 b through the spacer block as shown in FIG. 8. Insome examples, guide 418 may still be in place within tissue protector400. Once the parallel guide 300 is placed on tissue protector 400, anext guide 418 b is inserted through the parallel spacer reaching downto engage the bone (e.g., an ilium).

FIG. 9 illustrates a perspective view of an exemplary packing plunger500 placed in a dispensing tube 502. In some examples, dispensing tube502 and plunger 500 work together to dispense therapeutic material intothe cage located in the bone (e.g., ilium and/or sacrum). The plungerand the dispensing tube dispense various therapeutic materials (e.g.,liquids, gases, gels, or other materials. As described herein, suchtherapeutic materials include osteogenic compounds (e.g., bonemorphogenetic protein, or other osteogenic compounds that may ossifytissue in the joint), osteoconductive materials (e.g., demineralizedbone, hydroxyapatite, or other material that promotes bone growth),antibiotics, steroids, contrast materials, or other materials that maybeneficial to fusing the joint, treating inflammation or otherconditions in the joint, or enabling the visualization of the areawithin and adjacent to the cage. In some examples, plunger 500 may bedepressed to dispense material from dispensing tube 502, for example,into a cannulated cage (e.g., cages 100), which may in turn deliver saidmaterial into a joint, as described above, through the fenestrationsdiscussed above.

Although the foregoing examples have been described in some detail forpurposes of clarity of understanding, the invention is not limited tothe details provided. There are many alternative ways of implementingthe invention.

What is claimed is:
 1. A parallel spacer for parallel spacing of a guideduring surgery, the parallel spacer comprising: a parallel-spacer bodyhaving a top surface and a bottom surface, the parallel-spacer bodydefining a first guide aperture extending through the parallel-spacerbody between openings in the top and bottom surfaces and defined byinternal walls; and an external positioning protrusion extending fromthe bottom surface of the parallel-spacer body and ending in a lowersurface, the external positioning protrusion including an orientationfeature configured to receive a first guide in a first orientation andhold the parallel-spacer body in a body orientation with respect to thefirst guide and the first orientation, the orientation feature extendingthrough the external positioning protrusion and from the top surface ofthe parallel-spacer body to the lower surface of the externalpositioning protrusion, wherein: the first guide aperture is sized toreceive and hold another guide in a parallel orientation to the firstorientation, the first guide aperture being disposed to hold the otherguide at a first distance, from the orientation feature; the first guideaperture ends at a distal end surface that is a first distance from thetop surface of the parallel-spacer body; the lower surface of theexternal positioning protrusion is a second distance from the topsurface of the parallel-spacer body; and the first and second distancesare different.
 2. The parallel spacer of claim 1, wherein theorientation feature is configured to receive a pin or a wire as thefirst guide.
 3. The device of claim 1, wherein the first guide apertureis configured to receive a same size guide as the first guide, andwherein the internal walls of first guide aperture and an openingdefined by the orientation feature have a same size.
 4. The parallelspacer of claim 1, wherein the external positioning protrusion isconfigured to be received into at least one of a drill guide or a tissueprotector and constrain the drill guide or the tissue protector withrespect to the parallel-spacer body.
 5. The parallel spacer of claim 4,wherein the external positioning protrusion comprises a slot that isconfigured to flex when the external positioning protrusion is receivedinto the drill guide or the tissue protector such that an annular ridgeof the external positioning protrusion engages an internal wall of thedrill guide or the tissue protector.
 6. The parallel spacer of claim 1,wherein the external positioning protrusion is integrally formed withthe parallel-spacer body.
 7. The parallel spacer of claim 1, wherein anouter surface of the external positioning protrusion is parallel withthe internal walls of the first guide aperture.
 8. The parallel spacerof claim 1, wherein the external positioning protrusion is configured toengage a drill guide as the first guide to maintain the other guide in aparallel orientation to an orientation of the drill guide.
 9. Theparallel spacer of claim 1, further comprising additional guideapertures extending between additional openings in the top surface andadditional openings in the bottom surface and defined by internal walls.10. The parallel spacer of claim 9, wherein each of the additionalapertures are located at different distances from the orientationfeature.
 11. The parallel spacer of claim 9, further comprising at leasttwo spacer markings, with a first spacer marking positioned adjacent tothe first guide aperture and a second spacer marking positioned adjacentto one of the additional guide apertures on the parallel-spacer bodywith each of the two spacer markings marking a first linear distance anda second linear distance.
 12. The parallel spacer of claim 11, whereinthe parallel spacer body is configured to allow a user to position, at aselected one of the spacer markings, a second guide such that apredetermined discrete distance relative to a previously placed guide atthe orientation feature is established.
 13. The parallel spacer of claim1, further comprising additional guide apertures that are each sized toreceive the other guide and hold the other guide in a parallelorientation to the first orientation.
 14. The parallel spacer of claim1, further comprising additional guide apertures that are positioned inan alternating linear pattern progressing in distance from theorientation feature, with a first set of the additional guide aperturesfalling along a first line and a second set of the additional guideapertures falling along a second line.
 15. The parallel spacer of claim14, wherein: each of the additional guide apertures all define differentpoints that all define different lines with respect to the orientationfeature defining a first point in each of the different lines; and eachof the additional guide apertures are positioned on a curved line withrespect to one another.
 16. A parallel-spacer guide system, comprising:the parallel spacer of claim 1; and a tissue protector including ahollow shaft open at a first end and a second end, wherein the externalpositioning protrusion is configured and dimensioned for reception intothe hollow shaft, wherein the external positioning protrusion has aclose tolerance to the hollow shaft to maintain the other guide in aparallel orientation to an orientation of the tissue protector.
 17. Theparallel spacer of claim 1, wherein the distal end surface and thebottom surface of the parallel-spacer body are the same surface.
 18. Aparallel spacer for parallel spacing of a guide during surgery,comprising: a parallel-spacer body having a top surface and a bottomsurface, the parallel-spacer body defining a first guide apertureextending through the parallel-spacer body between openings in the topand bottom surfaces and defined by internal walls; and an externalpositioning protrusion extending from the bottom surface of theparallel-spacer body and ending in a lower surface, the externalpositioning protrusion including an orientation feature configured toreceive a first guide in a first orientation and hold theparallel-spacer body in a body orientation with respect to the firstguide and the first orientation, the orientation feature extendingthrough the external positioning protrusion from the top surface of theparallel-spacer body to the lower surface of the external positioningprotrusion, wherein: the first guide aperture is sized to receive andhold another guide having a same size as the first guide in a parallelorientation to the first orientation the first guide aperture ends at adistal end surface that is a first distance from the top surface of theparallel-spacer body; the lower surface of the external positioningprotrusion is a second distance from the top surface of theparallel-spacer body; and the first and second distances are different.19. The parallel spacer of claim 18, wherein the parallel-spacer body isconfigured to allow a user to position a second guide such that apredetermined discrete distance relative to a previously placed guide atthe orientation feature is established.
 20. The parallel spacer of claim18, wherein the external positioning protrusion is configured to bereceived into at least one of a drill guide or a tissue protector.